Airborne magnetic and radiometric study around oil shale mine area in Kohtla-Jarve, Estonia

The airborne geophysical study of the Kohtla-Järve oil shale area NE Estonia consists of electromagnetic, magnetic and radiometric measurements. This paper discusses the use of the magnetic and radiometric data sets for mapping geological structures at a sedimentary rock area, and for assessing environmental impacts of the mining of oil shale. The sedimentary rocks of the area are different types of middle Ordovician limestone, which is covered by a thin layer of Quaternary glacial sediments. General view of the airborne magnetic map arises from the Precambrian basement some 300 meters below the sedimentary rocks, while the appearance of the radiometric maps is prominently affected by wetlands. The magnetic and radiometric features of the sedimentary rocks are very weak, but the integrated interpretation of the airborne and other available data provided information relevant both for geological mapping and environmental issues.